In the second year of this project, we will continue to study the characteristics of pulsatile blood flow in experimental models of problems encountered in clinical vascular surgery. These include (1) end-to-side anastomosis, (2) arterial stenosis, and (3) arterial bifurcations. We will measure changes in flow, pressure, and total fluid energy which occur at each of these sites in the vascular system. These hemodynamic studies will be performed in vitro using plastic models and pulsatile pump. Additional studies will be performed using in vivo models in dogs. We will also continue our investigation of the phenomenon of boundary layer separation which occurs at each of these sites in the vascular system. These studies will be done in vitro using dye injection techniques in clear plastic models. The flow disturbances will be observed and recorded photographically. The hemodynamic forces leading to fluid separation by making multiple pressure measurements within the anastomosis, stenosis, or bifurcation. This information will be of direct value to vascular surgeons by providing information as to the optimum technique for arterial reconstruction relative to hemodynamics and fluid disturbances.